In several known metallurgical operations, metal powder is heated for various purposes, such as annealing of the powder, hot compaction of the powder, or coating of the powder. A "powder" is defined as a collection of particles. In several of the known applications, a compact made from the powder is heated to remove lubricants and to increase the compact cohesiveness (sintering). Most of the known heating techniques make use of radiant heat furnaces. While radiant heat is effective in heating compacts of metal particles that have metal to metal contact, they are ineffective in heating loose powder. This is because the thermal conductivity of a powder is less than that of a solid compact. For example, the thermal conductivity of iron powder is one hundred times less than that of a solid compact of iron.
In addition, induction heating (operating at 1000 Hz) has been known to produce eddy currents in metals and has been used for melting and heat treating solid metals. In connection with heating a metal powder, this technique would involve placing the powder in a solid container and employing induction to heat the container. The container would then transmit the heat to the powder. However, due to the poor heat conductivity of powder, this method is ineffective.